Handle keys only when EWW window is open.

eww.yuck

(defwindow window :windowtype "normal" :wm-ignore true
  :geometry (geometry :anchor "center" :y 100 :width "10%" :height "10%")
(key))

(deflisten log "./key.sh")
(defwidget key[] "This prints nohing. '${log}'")

;; vim:filetype=yuck

key.sh

#!/usr/bin/env bash

# depends on https://github.com/dharmx/xcore
xcore -Mkey | while read -r keytype key; do
  [[ "$keytype" == "KeyRelease" ]] && continue
  case "$key" in
    Return) dunstify "Return pressed!" ;;
    d) dunstify "D pressed!" ;;
    Super_L) dunstify "Super pressed!" ;;
  esac
done

demo.mp4